Crankshaft driven valve actuation

ABSTRACT

A hydraulic valve actuation system ( 30 ) and a method of assembly can include a plurality of hydraulically actuatable valves ( 34   a,    34   b,    34   c,    34   d,    134   a,    134   b,    134   c,    134   d ) operably associated with an internal combustion engine ( 86 ) having a crankshaft ( 50 ) rotatable about a longitudinal axis. The actuation system ( 30 ) can include at least one cam lobe ( 52 ) mounted on or integrally formed with the crankshaft for rotation with the crankshaft ( 50 ). At least one fluid piston pump ( 36, 36   a,    36   b ) connected to the at least one cam lobe ( 52 ) for generating a reciprocating fluid flow in response to rotation of the at least one cam lobe ( 52 ). At least one hydraulically actuated valve ( 34   a,    34   b,    34   c,    34   d,    134   a,    134   b,    134   c,    134   d ) in fluid communication with the reciprocal fluid flow generated by the at least one fluid piston pump ( 36, 36   a,    36   b ) to drive the valve ( 34   a,    34   b,    34   c,    34   d,    134   a,    134   b,    134   c,    134   d ) to be controlled toward an open position.

FIELD OF THE INVENTION

The invention relates to a method and apparatus for hydraulic actuationof valves in an internal combustion engine, and more particularly, tohydraulic actuation of intake and exhaust valves of an internalcombustion engine.

BACKGROUND

An internal combustion engine generates power by burning fuel in acombustion chamber. Current intake and exhaust valves can be controlledand operated by camshafts and cams located in the engine. Intake valvescan be opened in order to admit fuel and air into a cylinder forcombustion, while exhaust valves can be opened to allow combustion gasto escape from the cylinder. The cams can be fixed profile cams whichcan provide difficulty in adjusting timings or amounts of engine valvelifts needed to optimize valve opening times and lift for varying engineoperations. A lost motion device can be used between a valve and the camfor transmitting varying amounts of the cam motion to the valve. Currentlost motion systems use a master piston which displaces fluid from ahydraulic chamber into a hydraulic chamber of a slave piston. The slavepiston can act on the engine valve for opening the valve. The hydraulicsystem generally includes added components such as cam sensors, oilcontrol valves, phasers, guides, timing chains, tensioners, sprockets,bearing caps, and miscellaneous bolts and fasteners. The need for theadded components in order to operate a lost motion system can increasevalve train inertia, which can be problematic at high engine speeds. Theadded components can also increase complexity and cost such that it canbe desirable to minimize the additional components. Valve actuationsystems have been disclosed in U.S. Pat. No. 8,365,691; U.S. Pat. No.6,997,148; U.S. Pat. No. 6,425,357; U.S. Pat. No. 5,645,031; U.S. Pat.No. 4,716,863; U.S. Pat. No. 2,072,437; U.S. Patent Application No.2011/0197833; and W.O. Patent Application No. 2007/142724.

SUMMARY

It can also be desirable to eliminate the camshaft as an additionalcomponent due to the added size and weight of the camshaft to the valvetrain. To overcome the limitation of current technology, the disclosedhydraulic valve actuation system uses at least one cam lobe connected toa crankshaft to be driven in rotation for reciprocating a master pistonfor pressurizing fluid to drive reciprocal fluid flow within thehydraulic valve actuation system. The use of a cam lobe connecteddirectly to the crankshaft can eliminate added components currently usedin valve actuation systems such as the cam sensors, oil control valves,phasers, guides, timing chains, tensioners, sprockets, bearing caps, andmiscellaneous bolts and fasteners. The hydraulic valve actuation systemcan control the opening and closing of a plurality of hydraulicallyactuatable valves, either intake valves or exhaust valves, or bothintake and exhaust valves. The valves can be associated with a pluralityof cylinders of an internal combustion engine and can have acorresponding slave piston for each valve. Each of the plurality ofslave pistons can be normally biased by a spring toward a first positioncorresponding to the valve being in a closed valve position. The slavepiston can be driven toward a second position corresponding to the valvebeing in an open position by fluid pressure overcoming a biasing forceof the spring. The hydraulic valve actuation system can include at leastone accumulator operable for reciprocally receiving and releasing fluidin a lost motion manner when valve actuation is not desired, and formaintaining fluid pressure and volume in the hydraulic valve actuationsystem.

A hydraulic valve actuation system can include at least one fluidpressure piston pump having at least one reciprocal master piston formovement within a housing defining at least one fluid pumping chamber.The fluid piston pump can include at least one biasing spring forbiasing the corresponding reciprocal master piston toward a firstposition within the housing. The hydraulic valve actuation system caninclude a crankshaft rotatable about a longitudinal axis and having atleast one cam lobe carried on the crankshaft for rotation therewith. Theat least one cam lobe can be driven in rotation about the longitudinalrotational axis of the crankshaft and can be engageable with a camfollower connected to a corresponding reciprocal master piston. The camfollower can drive the at least one reciprocal master piston toward asecond position into the at least one fluid pumping chamber when drivenby the at least one cam lobe to pressurize the working fluid forreciprocal flow through the fluid passages of the hydraulic valveactuation system. The biasing spring can normally bias the correspondingreciprocal master piston and associated cam follower toward the firstposition and into continuous engagement with the at least one cam lobeof the crankshaft located outside of the pump chamber.

The at least one reciprocal master piston can be operable forpressurizing fluid located in the at least one fluid pumping chamberwhen driven by the at least one cam lobe mounted on the crankshaft toovercome the biasing force of the at least one biasing spring creatingsufficient working fluid pressure and volume to operably actuate one ormore of a plurality of valves in fluid communication with the hydraulicvalve actuation system as fluid flow reciprocates within the hydraulicvalve actuation system fluid passages in response to reciprocation ofthe master piston driven by the cam lobe mounted on and driven inrotation with the crankshaft. The pump chamber can be in fluidcommunication with the plurality of valves allowing pressurized fluidflow toward one or more of the plurality of valves during a drivenstroke of the reciprocal master piston by the cam lobe and allowingfluid flow to be drawn back into the pump chamber from one or more ofthe plurality of valves during a return stroke of the reciprocal masterpiston driven by the biasing spring. The pump chamber can also beoperable for fluid communication with the at least one accumulator formaintaining working fluid volume and pressure during the operating cycleand to make up for working fluid volume losses and pressure losses dueto normal leakage during operation cycles. The working fluid, being anessentially incompressible working fluid, can allow reciprocal flowingmovement of the working fluid through the hydraulic valve actuationsystem in response to reciprocal movement of the master piston as themaster piston reciprocal movement follows the cam lobe rotationcorresponding to rotation of the crankshaft. The master piston is incontinuous fluid communication with the hydraulic valve actuation systemfluid passages during operation of the internal combustion engine.

The hydraulic valve actuation system can further include at least onefirst control valve operable between a first position isolating fluidflow between the at least one accumulator and the hydraulic valveactuation system fluid passages and a second position for providingfluid communication between the hydraulic valve actuation system fluidpassages and the at least one accumulator. The at least one firstcontrol valve can provide for fluid communication between the at leastone fluid pressure piston pump and the at least one valve assembly.

A method of operating a normally closed valve of an internal combustionengine having a rotatable crankshaft can include driving reciprocalfluid flow within a fluid passage in response to rotation of thecrankshaft of the internal combustion engine, and selectivelycommunicating an expandable fluid chamber associated with a normallyclosed valve with the reciprocal fluid flow within the fluid passage forcyclically driving the normally closed valve between an open positionand a closed position in response to fluid flow within the passage. Themethod can include rotating a cam lobe mounted on a crankshaft of aninternal combustion engine, and driving at least one fluid pressurepiston pump having at least one reciprocal master piston in movementwithin a housing defining at least one fluid pumping chamber in responseto rotation of the cam lobe. The method can include biasing thecorresponding reciprocal master piston toward a first position withinthe housing with a spring for maintaining continuous contact between acam follower connected to the corresponding reciprocal master piston andthe rotating cam lobe.

A method of assembling a hydraulic valve actuation system can includemounting a cam lobe on a crankshaft of an internal combustion engine forrotation with the crankshaft, and connecting a cam follower to at leastone reciprocal master piston of at least one fluid pressure piston pumpfor driving reciprocal movement of the master piston in response torotation of the cam lobe driven in rotation by the crankshaft to createa reciprocal fluid flow cycle within a closed fluid flow path, andbiasing the master piston toward a first position for maintaining thecam follower in continuous contact with the cam lobe. The method caninclude connecting at least one valve for selectively allowing andpreventing fluid communication between an expandable fluid chamberoperably associated with a valve to be actuated and the closed fluidflow path carrying the reciprocal fluid flow driven by the reciprocalmovement of the master piston. The method can include connecting anengine control unit for selectively controlling fluid communication witheach of the expandable fluid chambers associated with a valve to beactuated to prevent and allow fluid communication during a reciprocalfluid flow cycle carried within the closed fluid flow path to open andclose each valve to be actuated in a predetermined sequence according tosignals received from an engine control unit. The method can includeconnecting at least one valve for selectively allowing and preventingfluid communication between the closed fluid flow path and at least oneaccumulator.

Other applications of the present invention will become apparent tothose skilled in the art when the following description of the best modecontemplated for practicing the invention is read in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views, and wherein:

FIG. 1 is a schematic view of a crankshaft driven valve actuation systemincluding a crankshaft, a valve assembly, either intake or exhaust, anda hydraulic valve actuation system illustrating a cam lobe mounted on acrankshaft and driven in rotation by the crankshaft of an internalcombustion engine, the cam lobe for driving a master piston inreciprocal movement between first and second positions to create areciprocal fluid flow within a closed fluid flow path, a first controlvalve illustrated in a first position for allowing fluid communicationbetween the master piston chamber and the valve assembly, and at leastone switching valve for selectively allowing and preventing fluidcommunication between an expandable fluid chamber associated with avalve to be actuated and the closed fluid flow path, wherein the atleast one switching valve is in a first position to allow fluidcommunication between the expandable fluid chamber for actuating a firstvalve associated with a first cylinder of an internal combustion engineand the reciprocal fluid flow within the closed fluid flow path, whilepreventing fluid communication between an expandable fluid chamber foractuating a second valve associated with a fourth cylinder of theinternal combustion engine and the reciprocal fluid flow within theclosed fluid flow path;

FIG. 2 is a schematic view of the crankshaft driven valve actuationsystem of FIG. 1 illustrating the at least one switching valve in asecond position for allowing fluid communication between the secondvalve associated with the fourth cylinder of the internal combustionengine and the reciprocal fluid flow within the closed fluid flow path,while preventing fluid communication between the first valve associatedwith the first cylinder of the internal combustion engine and thereciprocal fluid flow within the closed fluid flow path, where themaster piston is shown driven by the cam lobe angularly positioned at amaximum distance with respect to the master piston defining a firstposition forcing fluid into the closed fluid flow path from the masterpiston chamber;

FIG. 3 is a schematic view of the crankshaft driven valve actuationsystem of FIG. 1 illustrating the crankshaft rotated 180° from theposition shown in FIGS. 1 and 2 to angularly position the cam lobe at aminimum distance with respect to the master piston defining a secondposition drawing fluid from the closed fluid flow path back into themaster piston chamber;

FIG. 4 is a schematic view of the crankshaft driven valve actuationsystem of FIG. 1 illustrating the first control valve in a secondposition operable for allowing fluid communication between the masterpiston, an accumulator, and the valve assembly;

FIG. 5 is a schematic view of the crankshaft driven valve actuationsystem of FIG. 1, where continuous fluid communication between themaster piston chamber and the valve assembly is provided through apassage, and the first control valve is operable between a first closedposition and a second open position for selectively controlling fluidcommunication between the master piston chamber and the accumulator;

FIG. 6 is a simplified detailed perspective view of the crankshaftillustrating at least one cam lobe connected to the crankshaft withvarious engine components removed for clarity;

FIG. 7A is a perspective cross sectional view of the crankshaft drivenvalve actuation system;

FIG. 7B is a plan view of the crankshaft illustrating crankcounterweights;

FIG. 8A is a schematic view of the crankshaft driven valve actuationsystem for selectively controlling the opening of a single valveillustrating a first control valve operable between a first closedposition and a second open position for selectively controlling fluidcommunication between the master piston chamber and the accumulator forlost motion fluid flow when actuation of the single valve is notdesired;

FIG. 8B is a schematic view of the crankshaft driven valve actuationsystem for selectively controlling the opening of two valvesillustrating a first normally closed engine valve, a second normallyclosed engine valve, and a fluid switching valve in a second positionfor allowing fluid communication between the first valve and reciprocalfluid flow within the closed fluid flow path, while preventing fluidcommunication between the second valve and reciprocal fluid flow withinthe closed fluid flow path, where the master piston is shown driven bythe cam lobe angularly positioned at a maximum distance with respect tothe master piston defining a first position forcing fluid into theclosed fluid flow path from the master piston chamber; and

FIG. 9 is a schematic view of a crankshaft driven valve actuation systemfor selectively controlling four intake valves and four exhaust valvesincluding a crankshaft, an internal combustion engine valve assembly,including both intake and exhaust valves, and a hydraulic valveactuation system illustrating two cam lobes located at approximately220° with respect to one another connected to the crankshaft to bedriven in rotation by the crankshaft of an internal combustion enginefor driving first and second master pistons in reciprocal movementbetween first and second positions to create a reciprocal fluid flowwithin two separate closed fluid flow paths, four control valves, eachcontrol valve movable between a first position operable for allowingfluid communication between the master piston chamber and theaccumulator, and at least one switching valve for selectively allowingand preventing fluid communication between an expandable fluid chamberassociated with each valve to be actuated and the closed fluid flowpath.

DETAILED DESCRIPTION

Referring now to FIGS. 1-9, a crankshaft driven valve actuation system30 for controlling opening and closing of a plurality of hydraulicallyactuated valves 34 a, 34 b, either intake valves, exhaust valves, orboth intake and exhaust valves, corresponding to a plurality ofcylinders of an internal combustion engine 86 is illustrated. The systemcan include a plurality of slave pistons 44 a, 44 b corresponding to theplurality of valves 34 a, 34 b. Each of the plurality of slave pistons44 a, 44 b can be normally biased by a spring toward a normally closedvalve position, and can be hydraulically driven with fluid pressuresufficiently high to overcome the biasing force of the spring toward anopen valve position. The hydraulic valve actuation system 30 can includeat least one accumulator 46 operable for receiving and releasing fluidvolume for providing a lost motion fluid flow when valve actuation isnot desired, and for maintaining fluid pressure and volume in thehydraulic valve actuation system 30. By way of example and notlimitation, the hydraulic valve actuation system 30 can be used in afour-stroke internal combustion engine 86 having a plurality of valves34 a, 34 b, either hydraulically actuated intake valves, hydraulicallyactuated exhaust valves, or both hydraulically actuated intake andexhaust valves.

By way of example and not limitation, a four stroke—four cylinder cyclecan refer to travel of each engine piston between an intake stroke, acompression stroke, an ignition/combustion/power stroke, and an exhauststroke, such that the at least one cam lobe 52 can drive the masterpiston within the master piston chamber to force fluid into the closedfluid flow path in order to open one of the valves 34 a with the atleast one switching valve 70 in the position shown and the cam lobe inthe 0° position as illustrated in FIG. 1. By way of example and notlimitation, the valves 34 a, 34 b can correspond to intake valves orexhaust valves associated with a first and fourth cylinder or intakevalves or exhaust valves associated with a second and third cylinder ofan internal combustion engine. As illustrated in FIG. 8A, the crankshaftdriven valve actuation system 30 can operate directly to open a singleintake valve or a single exhaust valve. It should be recognized that aplurality of cam lobes 52 can be provided mounted on the crankshaft fordriving reciprocal fluid flow through separate closed fluid flow pathsfor opening each intake valve and/or each exhaust valve individually. Itshould further be recognized that a single lobe 52 can drive one masterpiston pump corresponding to one closed fluid flow path, or can drivemultiple master piston pumps corresponding to multiple closed fluid flowpaths, if the master piston pumps are offset angularly from one anotherby approximately 180° for operation of the same valve type, two intakevalves or two exhaust valves, or offset angularly from one another byapproximately 220° for operation of different type valves, e.g. oneintake and one exhaust valve. By way of example and not limitation, itshould also be recognized, as illustrated in FIG. 8B, that the openingand closing of two valves 34 a, 34 b, either intake or exhaust valves,for different cylinders of an internal combustion engine can be actuatedwith a single master piston pump 38 driving reciprocal fluid flow withina single closed fluid flow path, a single control valve 56, by way ofexample and not limitation a control valve having an actuator such as asolenoid operated actuator, a piezoelectric operated actuator, or anyother mechanically or electrically operated actuator for a controlvalve, selectively allowing communication with an accumulator 47 and asingle switching valve 64 for selectively directing reciprocal fluidflow to one of the two valves 34 a, 34 b to be controlled.

It should be recognized by those skilled in the art that the singleswitching valve can be replaced with two separate individually actuatedvalves, where each valve has a closed position and an open position forselectively directing fluid flow to a corresponding valve to becontrolled without departing from the disclosure of the presentinvention. It should be recognized by those skilled in the art that thecam lobe can be mounted directly to the crankshaft or can be formedintegrally with the crankshaft, in either case, the cam lobe is rotatedat crankshaft speed. It should further be recognized by those skilled inthe art, that additional master fluid piston pump chambers and closedfluid flow paths can be provided similar to the disclosure above toprovide hydraulic valve actuation of the exhaust valves. It should berecognized by those skilled in the art that the two cam lobesillustrated in FIG. 9 can be offset at different angular orientationswith respect to one another allowing control of intake valves from onelobe and exhaust valves from another lobe, or can include master fluidpiston pump chambers driven by cam followers located offset at differentangular orientations with respect to one another around the first camlobe allowing control of intake and exhaust valves for two cylindersfrom the first cam lobe, while the intake and exhaust valves for the twoother cylinders are controlled from the second cam lobe. In other words,the cam followers for a master fluid piston pump chamber for controllingexhaust valves can be located angularly offset approximately 220° fromthe master fluid piston pump chambers for controlling the correspondingintake valves for the same cylinder of the internal combustion enginewhile being driven by the same first cam lobe. Alternatively, the camfollowers for master fluid piston pump chambers for intake and exhaustvalve control can be driven by separate first and second cam lobes inthe same angular orientation while being located offset longitudinallyfrom one another while the cam followers are located offsetapproximately 220° from one another. Alternatively, the cam followersfor master fluid piston pump chambers for intake and exhaust valvecontrol can be driven by separate first and second cam lobes offsetlongitudinally from one another and in different angular orientationswith respect to one another allowing the cam followers and/or associatedmaster fluid piston pump chambers to be located in any desired angularorientation with respect to one another, even side by side if desired.

Each cam lobe 52 can include a cam follower for driving a master pistonpump for actuating at least one or more valves. A single cam lobe 52 candrive either two intake valves and two exhaust valves associated with afirst and fourth cylinder if cam followers are located angularly offsetby approximately 220° from one another, or two intake valves associatedwith the first and fourth cylinder and two intake valves associated witha second and third cylinder if cam followers are located angularlyoffset by approximately 180° from one another. In order for the singlecam lobe 52 to drive two intake valves and two exhaust valves associatedwith the first and fourth cylinder, or second and third cylinder,shorter hydraulic channel lengths can be used and the corresponding camfollowers can be located approximately 220° with respect to one another.In order for the single cam lobe 52 to drive two intake valvesassociated with the first and fourth cylinder and two intake valvesassociated with the second and third cylinder, the cam followers can belocated approximately 180° with respect to one another. Finally, itshould be recognized by those skilled in the art that the fourstroke—four cylinder engine cycle is by way of example and notlimitation, since the crankshaft driven hydraulic valve actuation systemcan be modified to accommodate different engine configurations, such asby way of example and not limitation, two or more cylinder engineconfigurations, such as three cylinder, six cylinder, eight cylinder, ormore than eight cylinder engine configurations without departing fromthe disclosure of the present invention.

The improvement of the hydraulic valve actuation system 30 can includeat least one fluid piston pump 36, a crankshaft 50, and at least onefirst control valve 56. The at least one fluid piston pump 36 caninclude at least one reciprocal master piston 38, at least one fluidpumping chamber 40, and at least one biasing spring 42. The biasingspring 42 can normally bias the master piston 38 toward a first positionwith respect to the pump chamber 40. The master piston 38 can beoperable for reciprocally driving fluid in and out of the pump chamber40 when driven by rotation of the crankshaft. The pump chamber 40 can bein continuous fluid communication with the plurality of valves 34 a, 34b, and can selectively be placed in fluid communication for fluid flowwith respect to the at least one accumulator 46. The crankshaft 50 canbe rotatable about a longitudinal axis and can have at least one camlobe 52 mounted to or integrally formed as part of the crankshaft forrotation with the crankshaft. The at least one cam lobe 52 can be drivenin rotation about the longitudinal axis and can be continuouslyengageable with a cam follower 54. The cam follower 54 can be connectedto the at least one reciprocal master piston 38 for reciprocal drivenmotion with respect to the at least one fluid pumping chamber 40 inresponse to rotation of at least one cam lobe 52. The at least one firstcontrol valve 56 can provide for fluid communication between the atleast one fluid pressure piston pump 36 and the at least one accumulator46.

Referring now to FIGS. 1-4, a hydraulic valve actuation system 30 caninclude a fluid piston pump 36 having a master piston 38, a pump chamber40, and a biasing spring 42 normally biasing the master piston 38 towarda first position with respect to the pump chamber 40. The master piston38 can reciprocally drive fluid into and out of the pump chamber 40 whendriven by rotation of the cam lobe 52. The pump chamber 40 can be incontinuous fluid communication with a plurality of valves 34 a, 34 b andcan be selectively in fluid communication with an accumulator 46 througha first control valve 56, by way of example and not limitation a controlvalve having an actuator such as a solenoid operated actuator, apiezoelectric operated actuator, or any other mechanically orelectrically operated actuator for a control valve. The crankshaft 50can be rotatable about a longitudinal axis and can have a cam lobe 52connected to the crankshaft 50 for rotation. The cam lobe 52 can berotatable with the crankshaft 50 about the longitudinal axis and cancontinuously engage a cam follower 54. The cam follower 54 can drive themaster piston 38 reciprocally with respect to the pump chamber 40 whendriven in response to rotation of the cam lobe 52. The hydraulic valveactuation system 30 can include a first control valve 56 and a secondcontrol valve 64.

As illustrated in FIG. 1, the first control valve 56 can provide forcontinuous fluid communication between the pump chamber 40 and a valveassembly 32 in a first position 62 and a second position 60, whileisolating the closed fluid flow passages from fluid communication withthe accumulator when in the first position 62 and providing selectivefluid communication with the accumulator 46 when in the second position60. With the first control valve 56 is in the first or second position62, 60 as illustrated in FIG. 1, the second control valve 64 canselectively switch fluid communication between the master piston 38 andone of a plurality of slave pistons 44 a, 44 b for driving thecorresponding engine valve 34 a, 34 b from a normally closed positiontoward an open position. The valve assembly 32 can include a pluralityof hydraulically actuated engine valves 34 a, 34 b. By way of exampleand not limitation, it is contemplated that the disclosed hydraulicvalve actuation system 30 can be used in any number of cylinders, by wayof example and not limitation, such as a one, two, three, four, six, oreight cylinder internal combustion engine 86.

In operation, rotation of the crankshaft 50 rotates the cam lobe 52 fordriving the master piston from a first position (shown in FIG. 3) towarda second position (shown in FIG. 1) within the fluid pump 36, as the camfollower 54 continuously engages with the cam lobe 52. Reciprocation ofthe master piston 38 can reciprocally drive fluid out of and drawworking fluid back into the pump chamber 40 for providing reciprocalfluid flow within a closed fluid flow path between the fluid pump 36 andthe valve assembly 32. The fluid can leave the pump chamber 40 and flowthrough the first control valve 56. The first control valve 56 caninclude a first valve position 62, a second valve position 60, and anactuator 58, by way of example and not limitation a control valve havingan actuator such as a solenoid operated actuator, a piezoelectricoperated actuator, or any other mechanically or electrically operatedactuator for a control valve, for changing between the first and secondvalve positions. As illustrated in FIGS. 1-2, the first valve position62 can provide fluid communication between the fluid pump 36 and thevalve assembly 32, while being isolated from fluid communication withthe accumulator 46. As illustrated in FIG. 4, the second valve position60 can provide fluid communication between the fluid pump 36 and thevalve assembly 32, while allowing fluid communication between theaccumulator 46, the fluid pump 36 and the valve assembly 32. In thefirst and second valve positions 60, 62, fluid flow can occur betweenthe fluid pump 36 and the valve assembly 32, as the cam lobe 52 isdriven in rotation about an axis of rotation thereby generating areciprocal movement of the master piston within the fluid pump 36.

A fluid reservoir or sump 90 can provide fluid to a fluid pump 92 fordelivery through a check valve 96 a to the accumulator 46 when the firstcontrol valve 56 is in either the first position 62, or the secondposition 60, and can additionally supply fluid to the pump chamber 40when the first control valve 56 is in the second position 60. Theaccumulator 46 can operate as a lost fluid motion reservoir when valveactuation is not desired during reciprocation of the fluid pump 36,while also acting as a pressurized fluid reservoir for holding a volumeof the fluid under pressure and for maintaining the fluid pressure andvolume in the hydraulic valve actuation assembly 30. In other words, theaccumulator 46 can be used to modify the shape of the timing curve andallow for lost motion in the hydraulic system by reducing motion of thevalve while directing fluid flow to the accumulator 46. The inclusion ofthe accumulator 46 in the system can allow a valve in fluidcommunication with the accumulator to open late, close early, openpartially, or prevent opening of the valve all together. The accumulator46 can include an accumulator spring 47 for maintaining pressure of thefluid in the absence of the pump 92 running. The accumulator 46 canprovide fluid flow to the hydraulic valve actuation assembly 30 when thefirst control valve 56 is in the second valve position 60 to replenishany fluid losses from the closed fluid flow path, dampen pressurefluctuations, and supply supplemental fluid pressure when required forchanges in valve timing operation or to assist valve operation duringengine startup.

The fluid can flow between the first control valve 56 and the secondcontrol valve 64. The second control valve 64 can be a high-speedswitching valve for switching or skipping fluid flow between each of theplurality of intake valves 34 a, 34 b. The switching or skippingfunction can be used to make use of the lost fluid motion that wouldotherwise occur when controlling a single engine valve function with thehydraulic valve actuation assembly 30. It is contemplated that more thanone switching valve could be used with an internal combustion engine 86having additional cylinders and intake/exhaust valves. By way of exampleand not limitation, as illustrated in FIG. 1, the second control valve64 can be in a first valve position 68 providing for fluid flow betweenthe fluid pump 36 and an engine valve 34 a corresponding to a firstcylinder. The engine valve 34 a can include a slave piston 44 a. Theslave piston 44 a can be normally biased away from the engine valve 34 aby a biasing spring 48 a. When the slave piston 44 a is pressurized bythe fluid flow, the force can overcome the spring force such that theslave piston 44 a can open the engine valve 34 a. Fluid can also bereturned from the expandable chamber of the slave piston 44 a associatedwith the engine valve 34 a to reciprocate back to the pump chamber 40after passing through a check valve 80 b and/or by reversing fluid flowdirection through the second control valve 64. As illustrated in FIG. 1,the second control valve 64 when in the first position 68 can preventfluid flow to the engine valve 34 b corresponding to a third cylinder.Fluid flowing through the first control valve 56 can flow towards thesecond control valve 64, while being prevented from flowing directly toengine valve 34 a by check valve 80 b and to the engine valve 34 b by acheck valve 80 c.

As illustrated in FIG. 2, when the second control valve 64 is in thesecond valve position 70, the fluid can flow between the fluid pump 36and the engine valve 34 b. The engine valve 34 b can include a slavepiston 44 b. The slave piston 44 b can be normally biased away from theengine valve 34 b by a biasing spring 48 b. When the slave piston 44 bis pressurized by the fluid flow, the force can overcome the springforce such that the slave piston 44 b can open the engine valve 34 b.Fluid can also be returned from the expandable chamber of the slavepiston 44 b associated with the engine valve 34 b to reciprocate back tothe pump chamber 40 by reverse flow through second control valve 64 whenin the second position 70 and/or through check valve 80 c during thereturn stroke of piston 38. As illustrated in FIG. 2, the second controlvalve 64 when in the second position 70 can prevent fluid flow to theengine valve 34 a corresponding to the first cylinder. When the secondcontrol valve 64 is in the second valve position 70, fluid flowingthrough the first control valve 56 can flow towards the second controlvalve 64, while being prevented from flowing directly to the enginevalve 34 a by the check valve 80 b and to the engine valve 34 b by checkvalve 80 c. As illustrated in FIG. 3, the crankshaft 50 can be rotatablesuch that the cam lobe 52 is in a position 180° from the position shownin FIG. 1 with the cam follower 54 maintained in contact with the camlobe by force from biasing spring 42 as the master piston 38 is returnedto the first position.

As illustrated in FIG. 5, the first control valve 156 can isolate thepump chamber 40 from fluid communication with the accumulator 46 when ina first position 160, while providing for fluid communication betweenthe pump chamber 40 and the accumulator 46 when in a second position162. In the configuration illustrated in FIG. 5, the pump chamber 40 canbe in constant fluid communication with the engine valve assembly 32while the first control valve 156 provides a selectively controlledopened/closed function with respect to the accumulator 46 through thefirst control valve 156. The first control valve 156 can include a firstvalve position 160, a second valve position 162, and an actuator 158, byway of example and not limitation a control valve having an actuatorsuch as a solenoid operated actuator, a piezoelectric operated actuator,or any other mechanically or electrically operated actuator for acontrol valve. As illustrated in FIG. 5, the first valve position 160can prevent fluid communication between the accumulator 46 and the fluidpump 36, effectively isolating the reciprocal closed fluid flow pathfrom the accumulator 46. The second valve position 162 can provide forfluid communication between the reciprocal closed fluid flow path, thefluid pump 36, and the accumulator 46. Reciprocal fluid flow through theclosed fluid flow path can constantly occur between the fluid pump 36and the engine valve assembly 32 in response to the cam lobe 52 drivingreciprocation of the piston 38 of the fluid pump 36 independent of thefirst control valve 156 being in either the first or second positions160, 162.

Referring now to FIGS. 6-7B, the hydraulic valve actuation system 30disclosed can be used in a four cylinder internal combustion engine 86.FIG. 6 shows eight control valves 70 a corresponding to the fourcylinders. Each cylinder can have a set of intake valves 34 a, 234 a anda set of exhaust valves 134 a, 334 a. Each of the eight control valves70 a can correspond to two intake valves 34 a, 34 b and two exhaustvalves 134 a, 134 b. The disclosed hydraulic valve actuation system 30can be used for cylinders having a four-stroke cycle, but it iscontemplated that the system could be used in a two-stroke engine. It iscontemplated that a plurality of engine valve assemblies 32 could beused in the internal combustion engine 86 for controlling intake andexhaust valves as illustrated in FIG. 9.

As illustrated in FIGS. 6, 7B and 8B, it is contemplated that thecrankshaft 50 can include at least one crank counterweight 76. Thecrankshaft 50 can be driven by a plurality of pistons 94 associated withthe engine 86. Rotation of the crankshaft 50 can drive rotation of theat least one cam lobe 52 mounted on or formed integrally with thecrankshaft for driving reciprocal movement of at least one reciprocalmaster piston 38, 38 a, 38 b. The first reciprocal master piston 38, 38a, 38 b can control actuation of two engine valves for two pistons ofthe four cylinders similar to that shown and described in FIGS. 1-4. Aswitching valve 70 can control the opening and closing of two enginevalves 34 a, 34 b. The crank counterweight 76 can counterbalance massadded to the crankshaft 50. The at least one crank counterweight 76 canbe mounted to the crankshaft 50. As illustrated in FIG. 8B, a camfollower 54 can be normally biased against the at least one cam lobe 52by a spring and can convert the rotational movement from the crankshaft50 into the reciprocal movement of the at least one reciprocal masterpiston 38. In the four cylinder combustion engine, a first cam follower54 a and a second cam follower 54 b can correspond to the first andsecond reciprocal master piston 38 a, 38 b. It is also contemplated thatthe crankshaft 50 can have more than one cam lobe 52 connected to orintegrally from on the crankshaft to be driven in rotation about thelongitudinal axis of the crankshaft 50. In a four cylinder engine 86,the cam lobes 52, if separate cam lobes 52 are provided, or camfollowers 54 a, 54 b, if a single cam lobe 52 is used, can preferably belocated angularly offset by approximately 220° from each other foroperation of intake or exhaust valves. In a four-stroke engine 86, twointake and two exhaust valves corresponding to two cylinders can sharethe at least one cam lobe 52 with cam followers 54 a, 54 b locatedapproximately 220° angularly offset from one another for driving acorresponding reciprocal master piston 38 a, 38 b. The at least one camlobe 52 can rotate at a crankshaft speed corresponding to the rotationof the crankshaft 50. The plurality of slave pistons 44 a, 44 bcorresponding to the plurality of engine valves 34 a, 34 b can beswitched on alternative revolutions of the crankshaft 50.

The hydraulic valve actuation system 30 can further include a controlsystem, or electronic engine control unit 98, for operation. The controlsystem can include at least one controller and sensor in electricalconnection with the at least one first control valve 56 and the at leastone second control valve 64. The controller can include an electroniccontrol module having at least one microprocessor and at least onememory module. The controller can be adapted to control the actuation ofthe at least one first control valve 56 and the at least one secondcontrol valve 64 in response to a control program stored in memory basedon signals received from one or more sensors. The sensors can detect acam angle of the at least one cam lobe 52 with respect to the crankshaft50. The controller can control the operation of the internal combustionengine 86, such as the operation of the sump pump 92, control valves 70,70 a, and control valves 56, 156, 64

Advantages of implementing the disclosed hydraulic actuation system 30in an engine 86 include weight savings by eliminating additionalcomponents such as cam sensors, oil control valves, phasers, guides,timing chains, tensioners, sprockets, bearing caps, and miscellaneousbolts and fasteners. The disclosed hydraulic actuation system 30 canalso reduce parasitic losses in the engine 86 resulting from the use andwear of the additional components. The package size of the engine 86 canalso be reduced significantly by particularly removing camshafts. Thedisclosed hydraulic valve actuation system 30 can provide significanteconomic advantages by reducing production costs associated with theengine 86 due to removing the cost of the additional components. The useof multiple control valves and cam lobes can also provide flexibility ofintake and exhaust valve motion control including control of advance andretard timing events for valves.

A method of assembling a hydraulic valve actuation system 30 forcontrolling the opening and closing of a plurality of hydraulicallyactuatable valves 34 a, 34 b corresponding to a plurality of cylindersof an internal combustion engine 86 having a crankshaft can includemounting a cam lobe on the crankshaft for rotation with the crankshaft,driving reciprocation of at least one fluid pressure piston pump 36 inresponse to rotation of the cam lobe by the crankshaft, connecting theat least one fluid pressure piston pump 36 to a closed fluid flow pathfor directing reciprocal fluid flow from the at least on fluid pressurepiston pump 36 in fluid communication with at least one valve to becontrolled, and inserting at least one control valve 56 within thereciprocal closed fluid path for selectively directing reciprocal fluidflow between at least one valve to be controlled. The method can alsoinclude positioning a cam follower 54 between the cam lobe and the fluidpressure piston pump 36. The method can include hydraulically actuatingat least one engine valve 34 a, 34 b with at least one slave piston 44a, 44 b, biasing each of the slave pistons 44 a, 44 b normally toward aclosed valve position, selectively applying fluid pressure to selectedslave pistons to drive the valve to be controlled toward the openposition. The method can also include providing lost fluid motion andmaintaining fluid volume and pressure in the hydraulic valve actuationsystem 30 with at least one accumulator 46 operable for receiving andreleasing pressurized fluid into the reciprocal closed fluid flow path.The method can also include reciprocating at least one master piston 38within at least one fluid pumping chamber 40 of at least one fluidpressure piston pump 36 for generating reciprocal fluid flow in responseto rotation of the cam lobe, and biasing the at least one master piston38 toward a first position with at least one biasing spring 42. Themethod can also include positioning a cam follower 54 interposed betweenthe at least one cam lobe 52 and the at least one fluid pressure pistonpump 36.

Referring now to FIG. 9, a hydraulic valve actuation system 30 caninclude at least one cam lobe 52 a, 52 b and at least one fluid pistonpump 36 a, 36 b, 36 c, 36 d having a master piston 38 a, 38 b, 38 c, 38d, a pump chamber 40 a, 40 b, 40 c, 40 d and a biasing spring 42 a, 42b, 42 c, 42 d normally biasing the master piston 38 a, 38 b, 38 c, 38 dtoward a first position with respect to the pump chamber 40 a, 40 b, 40c, 40 d, where the master piston 38 a, 38 b, 38 c, 38 d draws fluid intoan enlarged volume pump chamber 40 a, 40 b, 40 c, 40 d. By way ofexample and not limitation, each of the at least one cam lobe 52 a, 52 bcan correspond to two fluid piston pumps 36 a, 36 b, 36 c, 36 d. Themaster piston 38 a, 38 b, 38 c, 38 d can reciprocally drive fluid intoand out of the pump chamber 40 a, 40 b, 40 c, 40 d when driven byrotation of the cam lobe 52 a, 52 b to a second position with respect tothe pump chamber 40 a, 40 b, 40 c, 40 d, where the master piston 38 a,38 b, 38 c, 38 d expels fluid from a reduced volume pump chamber 40 a,40 b, 40 c, 40 d. The pump chamber 40 a, 40 b, 40 c, 40 d can be incontinuous reciprocal fluid communication with a plurality of valves 34a, 34 b; 34 c, 34 d; 134 a, 134 b; 134 c, 134 d through separate closedfluid flow paths independently driven by master piston 38 a, 38 b, 38 c,38 d, and can be selectively in fluid communication with an accumulator46 a, 46 b, 46 c, 46 d through a first control valve 56 a, 56 b, 56 c,56 d, by way of example and not limitation a control valve having anactuator such as a solenoid operated actuator, a piezoelectric operatedactuator, or any other mechanically or electrically operated actuatorfor a control valve. The crankshaft 50 can be rotatable about alongitudinal axis. A first and second cam lobe 52 a, 52 b can be mountedon or integrally formed with the crankshaft 50 for rotation. By way ofexample and not limitation, the first and second cam lobe 52 a, 52 b canbe mounted on or integrally formed with the crankshaft 50 atapproximately 220° with respect to one another, such that the first camlobe 52 a can correspond to operation of intake valves 34 a, 34 b, 34 a,34 b associated with four cylinders of the internal combustion engine,while the second cam lobe 52 b can correspond to operation of theexhaust valves 134 a, 134 b, 134 c, 134 d.

In either case, the cam lobe 52 a, 52 b can be rotatable in response torotation of the crankshaft 50 about the longitudinal axis and can becontinuously engaged by a cam follower 54 a, 54 b 54 c, 54 d. The camfollower 54 a, 54 b, 54 c, 54 d can drive the corresponding masterpiston 38 a, 38 b, 38 c, 38 d reciprocally with respect to thecorresponding pump chamber 40 a, 40 b, 40 c, 40 d when driven inresponse to rotation of the cam lobe 52 a, 52 b. The hydraulic valveactuation system 30 can include a first control valve 56 a, 56 b, 56 c,56 d and second control valve 64 a, 64 b, 64 c, 64 d, by way of exampleand not limitation a control valve having an actuator such as a solenoidoperated actuator, a piezoelectric operated actuator, or any othermechanically or electrically operated actuator for a control valve. Asillustrated in FIG. 9, the first control valve 56 a, 56 b, 56 c, 56 dcan provide for reciprocal continuous fluid communication between thepump chamber 40 a, 40 b, 40 c, 40 d and an accumulator 46 a, 46 b, 46 c,46 d in second position 62 a, 62 b, 62 c, 62 d, while isolating theclosed fluid flow passages from fluid communication with an accumulator46 a, 46 b, 46 c, 46 d when in the first position 60 a, 60 b, 60 c, 60d. With the first control valve 56 a in either the first or secondposition 60 a, 62 a as illustrated in FIG. 9, the second control valve64 a can selectively switch fluid communication between the masterpiston 38 a, 38 b, 38 c, 38 d and one of a plurality of slave pistons 44a, 44 b, 44 c, 44 d, 144 a, 144 b, 144 c, 144 d for driving thecorresponding valve 34 a, 34 b, 34 c, 34 d, 134 a, 134 b, 134 c, 134 dfrom a normally closed position toward an open position. The valveassembly can include a plurality of hydraulically actuated valves 34 a,34 b, 34 c, 34 d, 134 a, 134 b, 134 c, 134 d. By way of example and notlimitation, it is contemplated that the disclosed hydraulic valveactuation system 30 can be used in an internal combustion engine havingany number of cylinders, such as a two, three, four, six, or eightcylinder internal combustion engine 86. By way of example and notlimitation, as illustrated in FIG. 1 and FIGS. 8A-9, the presentembodiment can be used in a four cylinder internal combustion engine 86and can include intake valves 34 a, 34 b, 34 c, 34 b and exhaust valves134 a, 134 b, 134 c, 134 d.

Fluid can also be returned from the expandable chambers of the slavepistons 44 a, 44 b, 44 c, 44 d, 144 a, 144 b, 144 c, 144 d associatedwith the valve 34 a, 34 b, 34 c, 34 d, 134 a, 134 b, 134 c, 134 d toreciprocate back to the pump chamber 40 a, 40 b, 40 c, 40 d afterpassing through optional check valve 80 b, 80 c; 180 b, 180 c; 80 d, 80e, 180 d, 180 e and/or by reversing fluid flow direction through thesecond control valve 64 a, 64 b, 64 c, 64 d. The second control valve 64a, 64 b, 64 c, 64 d can be in the first position 68 a, 68 b, 68 c, 68 dpreventing fluid flow to one of the two valves associated with thesecond control valve 64 a, 64 b, 64 c, 64 d.

As illustrated in FIG. 9, the engine control unit 98 can control theoperation of the control valves 56 a, 56 b, 56 c, 56 d, 64 a, 64 b, 64c, 64 d and pumps 92 a, 92 b, 92 c, 92 d by control signals generated inaccordance with a control program stored in memory in response tocontrol signals received by the engine control unit 98 from sensors (notshown).

In operation, as illustrated in FIG. 9, with the first cam lobe 52 ainitially shown in a 0° angular position and the second cam lobe 52 blocated approximately 220° with respect to the first cam lobe 52 a forpurposes of this description, the control valves 64 a, 64 b, 64 c, 64 dinitially positioned as illustrated in positions 68 a, 68 b, 68 c, 68 d.As the cam lobes 52 a, 52 b rotates through to a 180° angular positionfrom that illustrated, the control valves 64 a, 64 b, 64 c, 64 dtransition into positions 68 a, 68 b, 70 c, 70 d. As the cam lobes 52 a,52 b rotates through from the 180° angular orientation toward a 360°angular orientation, the control valves 64 a, 64 b, 64 c, 64 dtransition into positions 70 a, 70 b, 70 c, 70 d. As the cam lobes 52 a,52 b rotates through from 360° toward 540°, the control valves 64 a, 64b, 64 c, 64 d transition into positions 70 a, 70 b, 68 c, 68 d. As thecam lobes 52 a, 52 b rotates through 540° toward 720° (i.e. completing asecond 360° rotation), the control valves 64 a, 64 b, 64 c, 64 dtransition back into initial positions 68 a, 68 b, 68 c, 68 d and thecycle repeats. It should be recognized that the software program canchange the duration and degree of opening defining a valve actuationcurve of each valve as desired according to the control program storedin memory for execution by the engine control unit 98.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims, which scope is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructures as is permitted under the law.

What is claimed is:
 1. In a hydraulic valve actuation system (30) forcontrolling opening and closing a plurality of hydraulically actuatedvalves (34 a, 34 b, 34 c, 34 d, 134 a, 134 b, 134 c, 134 d) associatedwith an internal combustion engine (86) having a crankshaft (50)rotatable about a longitudinal axis, the improvement comprising: atleast one cam lobe (52, 52 a, 52 b) mounted on the crankshaft (50) to bedriven in rotation with the crankshaft (50); at least one fluid pistonpump (36, 36 a, 36 b, 36 c, 36 d) operably connected to the at least onecam lobe (52, 52 a, 52 b) for generating a reciprocating fluid flow inresponse to rotation of the at least one cam lobe (52, 52 a, 52 b); andat least one hydraulically actuated valve (34 a, 34 b, 34 c, 34 d, 134a, 134 b, 134 c, 134 d) in fluid communication with the reciprocatingfluid flow to drive the at least one hydraulically actuated valve (34 a,34 b, 34 c, 34 d, 134 a, 134 b, 134 c, 134 d) between a normally closedposition and an open position.
 2. The improvement of claim 1 furthercomprising: at least one accumulator (46 a, 46 b, 46 c, 46 d) forproviding lost fluid flow motion to prevent valve actuation in responseto the reciprocating fluid flow; and at least one first control valve(56, 56 a, 56 b, 56 c, 56 d) for selectively placing the reciprocatingfluid flow in fluid communication with the at least one accumulator (46a, 46 b, 46 c, 46 d).
 3. The improvement of claim 1 further comprising:the at least one hydraulically actuated valves including a firsthydraulically actuated valve (34 a, 34 c, 134 a, 134 c) and a secondhydraulically actuated valve (34 b, 34 d, 134 b, 134 d); and at leastone second control valve (64, 64 a, 64 b, 64 c, 64 d) for selectivelycontrolling fluid communication between the reciprocating fluid flow andone of the first hydraulically actuated valve (34 a, 34 c, 134 a, 134 c)and the second hydraulically actuated valve (34 b, 34 d, 134 b, 134 d).4. The improvement of claim 1 further comprising: a slave piston (44 a,44 b, 44 c, 44 d, 144 a, 144 b, 144 c, 144 d) connected to each of theat least one hydraulically actuated valves (34 a, 34 b, 34 c, 34 d, 134a, 134 b, 134 c, 134 d) to be controlled, each slave piston (44 a, 44 b,44 c, 44 d, 144 a, 144 b, 144 c, 144 d) normally biased toward a closedvalve position, each slave piston (44 a, 44 b, 44 c, 44 d, 144 a, 144 b,144 c, 144 d) driven by reciprocating fluid flow toward an open valveposition.
 5. The improvement of claim 1, wherein the at least one fluidpiston pump (36, 36 a, 36 b, 36 c, 36 d) further comprises: at least onereciprocal master piston (38, 38 a, 38 b, 38 c, 38 d), at least onefluid pumping chamber (40, 40 a, 40 b, 40 c, 40 d), and at least onebiasing spring (42, 42 a, 42 b, 42 c, 42 d), the biasing spring (42, 42a, 42 b, 42 c, 42 d) normally biasing the master piston (38, 38 a, 38 b,38 c, 38 d) into engagement with the at least one cam lobe (52, 52 a, 52b), the master piston (38, 38 a, 38 b, 38 c, 38 d) for reciprocallydriving fluid in and out with respect to the at least one fluid pumpingchamber (40, 40 a, 40 b, 40 c, 40 d).
 6. The improvement of claim 1further comprising: a cam follower (54, 54 a, 54 b, 54 c, 54 d) locatedbetween the at least one cam lobe (52, 52 a, 52 b) and the at least onefluid piston pump (36, 36 a, 36 b, 36 c, 36 d), the cam follower (54, 54a, 54 b, 54 c, 54 d) reciprocally driving the at least one fluid pistonpump (36, 36 a, 36 b, 36 c, 36 d) in response to rotation of the atleast one cam lobe (52 a, 52 b).
 7. A hydraulic valve actuation system(30) for an internal combustion engine (86) having a crankshaft (50)rotatable about a longitudinal axis comprising: a cam lobe (52, 52 a, 52b) mounted on the crankshaft to be driven in rotation with thecrankshaft (50); a fluid piston pump (36, 36 a, 35 b, 36 c, 36 d)connected to the cam lobe (52, 52 a, 52 b) for generating areciprocating fluid flow in response to rotation of the cam lobe (52, 52a, 52 b); and a hydraulically actuated valve (34 a, 34 b, 34 c, 34 d,134 a, 134 b, 134 c, 134 d) in fluid communication with thereciprocating fluid flow to drive the hydraulically actuated valve (34a, 34 b, 34 c, 34 d, 134 a, 134 b, 134 c, 134 d) between a normallyclosed position and an open position.
 8. The hydraulic valve actuationsystem (30) of claim 7 further comprising: an accumulator (46 a, 46 b,46 c, 46 d) for providing lost fluid flow motion to prevent valveactuation in response to the reciprocating fluid flow; and a firstcontrol valve (56, 56 a, 56 b, 56 c, 56 d) for selectively placing thereciprocating fluid flow in fluid communication with the accumulator (46a, 46 b, 46 c, 46 d).
 9. The hydraulic valve actuation system (30) ofclaim 7 further comprising: the hydraulically actuated valve including afirst hydraulically actuated valve (34 a, 34 c, 134 a, 134 c) and asecond hydraulically actuated valve (34 b, 34 d, 134 b, 134 d); and asecond control valve (64, 64 a, 64 b, 64 c, 64 d) for selectivelycontrolling fluid communication between the reciprocating fluid flow andone of the first hydraulically actuated valve (34 a, 34 c, 134 a, 134 c)and the second hydraulically actuated valve (34 b, 34 d, 134 b, 134 d).10. The hydraulic valve actuation system (30) of claim 7 furthercomprising: a slave piston (44 a, 44 b, 44 c, 44 d, 144 a, 144 b, 144 c,144 d) connected to the valve (34 a, 34 b, 34 c, 34 d, 134 a, 134 b, 134c, 134 d) to be controlled, the slave piston (44 a, 44 b, 44 c, 44 d,144 a, 144 b, 144 c, 144 d) normally biased toward a closed valveposition and driven by reciprocating fluid flow toward an open valveposition.
 11. The hydraulic valve actuation system (30) of claim 7,wherein the fluid piston pump (36) further comprises: a reciprocalmaster piston (38), a fluid pumping chamber (40), and a biasing spring(42), the biasing spring (42) normally biasing the master piston (38)into engagement with the cam lobe (52), the master piston (38) operablefor reciprocally driving fluid in and out with respect to the fluidpumping chamber (40).
 12. The hydraulic valve actuation system (30) ofclaim 7 further comprising: a cam follower (54) located between the camlobe (52) and the fluid piston pump (36), the cam follower (54)reciprocally driving the at least one fluid piston pump (36) in responseto rotation of the cam lobe (52).
 13. A method of assembling a hydraulicvalve actuation system (30) for controlling opening and closing aplurality of hydraulically actuated valves (34 a, 34 b, 34 c, 34 d, 134a, 134 b, 134 c, 134 d) corresponding to a plurality of cylinders of aninternal combustion engine (86) having a crankshaft (50) rotatable abouta longitudinal axis, the method comprising: forming a cam lobe (52, 52a, 52 b) connected to the crankshaft for rotation with the crankshaft(50); assembling a fluid pressure piston pump (36, 36 a, 36 b, 3) forgenerating a reciprocating fluid flow in response to rotation of the camlobe (52) by the crankshaft (50); and connecting at least onehydraulically actuated valve (34 a, 34 b, 34 c, 34 d, 134 a, 134 b, 134c, 134 d) to be controlled in fluid communication with the reciprocatingfluid flow from the fluid pressure piston pump (36, 36 a, 36 b, 36 c, 36d).
 14. The method of claim 13 further comprising: connecting a firstcontrol valve (56, 56 a, 56 b, 56 c, 56 d) for selectively directingreciprocal fluid flow between the fluid pressure piston pump (36, 36 a,36 b, 36 c, 36 d) and an accumulator (46, 46 a, 46 b, 46 c, 46 d) toprevent actuation of the at least one hydraulically actuated valve (34a, 34 b, 34 c, 34 d, 134 a, 134 b, 134 c, 134 d) to be controlled. 15.The method of claim 13 further comprising: assembling the at least onehydraulically actuated valve to include a first hydraulically actuatedvalve (34 a, 34 c, 134 a, 134 c) and a second hydraulically actuatedvalve (34 b, 34 d, 134 b, 134 d); and connecting a second control valve(64, 64 a, 64 b, 64 c, 64 d) for selectively controlling fluidcommunication between the reciprocating fluid flow and one of the firsthydraulically actuated valve (34 a, 34 c, 134 a, 134 c) and the secondhydraulically actuated valve (34 b, 34 d, 134 b, 134 d).